JP2000255803A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely drive a stepping motor by changing the through up control of the stepping motor according to the sort of a paper sheet judged by a paper sheet sort judging means. SOLUTION: Whether paper feed requirement exists or not, is judged (Step1), and when the paper feed requirement exists, the sort of a paper sheet is judged (Step2) by judgement of the sort of a paper sheet. When the judgement result is ordinary paper, to control by through up control 1 (Step3), when the paper sheet is a special paper except the ordinary paper, to control by through up control 2 (Step4), respectively the control is changed. Hereby, a stepping motor can be surely driven and because a small-sized stepping motor can be used, the cost can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus using a stepping motor.

[0002]

2. Description of the Related Art In an image forming apparatus of this type, a stepping motor is usually used for driving paper to be fed. Generally, this stepping motor is often used outside the self-starting area from the viewpoint of cost and the like, and therefore, at the time of starting the motor drive (at the time of start-up), a through-up control for performing excitation switching in chronological order is performed. Have been done. FIG. 7 is a characteristic diagram showing normal through-up control.
On the vertical axis is the "speed of the stepping motor (rad / s)"
, And the horizontal axis indicates “time (sec)”.
That is, as shown in FIG. 7, the rotation speed is usually gradually increased from the start of the stepping motor, and the pulse rotation speed is increased in a time series. The rotation of the motor reaches the steady rotation. Further, as a prior art of such a through-up control, Japanese Patent Application Laid-Open No. H10-120237 discloses that when a paper feeding failure occurs after a through-up operation, paper feeding is performed again, and the through-up time is made longer than the previous time. This describes a control technique that can prevent defective paper feeding and can use an inexpensive motor.

[0003]

However, in the case of the conventional image forming apparatus, the following problems may occur. That is, when the through-up control is started, the rotation speed of the stepping motor changes, and the inertia force has the greatest influence. Therefore, the load on the stepping motor increases. For this reason, in order to reliably drive the stepping motor, it is necessary to consider a considerable margin in the motor capacity in the related art, so that a small and inexpensive motor cannot be used. As a result, there has been a problem that the image forming apparatus itself becomes large in size and causes an increase in cost.

In the case of the technology described in the conventional gazette,
For example, when feeding a paper type with a relatively large load, such as an envelope, there is still a high possibility that a paper feed failure due to a motor step-out or the like will occur. To prevent this, a large and expensive motor must be used. It becomes necessary to use it, and there is a problem from the viewpoint of cost.

Accordingly, an object of the present invention is to solve the above-mentioned problems of the conventional image forming apparatus, to surely drive the stepping motor and to use a small and inexpensive stepping motor. An object of the present invention is to provide an image forming apparatus capable of reducing costs.

[0006]

According to the present invention, in order to achieve the above-mentioned object, the invention according to the first aspect is characterized in that a paper feeding means for feeding paper and a driving of the paper feeding means are provided. In an image forming apparatus having a stepping motor to be used and a paper type determining unit for determining a paper type of the paper, through-up control of the stepping motor is switched according to the type of the paper determined by the paper type determining unit. It is characterized by the following.

According to a second aspect of the present invention, in the first aspect of the present invention, when feeding a sheet having a large load on the stepping motor at the time of sheet feeding, a slew-up control for increasing a slew-up time of the stepping motor is provided. Is performed.

According to a third aspect of the present invention, in the first aspect of the present invention, there is provided a paper size detecting means for determining a paper type having a large load on the stepping motor as a specific size. And step-up control of the stepping motor can be switched in accordance with the sheet size between the normal size and the normal size.

[0009]

FIG. 1 is a schematic diagram showing an image forming apparatus according to the present invention. As shown in FIG. 1, the image forming apparatus 1 has a photosensitive drum 2 for forming an image,
The photosensitive drum 2 is driven to rotate by a main motor (not shown), and the surface thereof is uniformly charged by a charging roller 3.
Is irradiated with a laser beam from the optical unit 8 to form an electrostatic latent image. This electrostatic latent image is visualized by a developing process by the developing roller 11. On the other hand, paper is placed in the paper feed tray 9, and the paper is fed by a paper feed roller 10 and transported to the registration roller 6. The registration roller 6 aligns the leading edge of the image. The visible image on the photosensitive drum 2 is transferred to the transfer roller 5.
Is transferred onto the sheet conveyed via the registration roller 6, and is fixed by heating and pressing by the fixing unit 7 and is discharged. Manual paper feed is performed by the manual tray 12.

FIG. 2 is a block diagram of a control system applied to the image forming apparatus of the present invention. As shown in FIG. 2, the control of the entire image forming apparatus 1 is performed by the main control unit 13. The main control unit 13 has a controller 14 for sending an image forming instruction, various sensors for detecting “paper type” and “paper size” and detecting a fixing temperature.
15, a writing unit 16, a high voltage unit 17, and a fixing unit 18 are connected. Further, the stepping motor 20 is connected via a driver 19.

FIG. 3 is a flowchart showing a first embodiment of the present invention. That is, first, it is determined whether or not there is a paper feed request (Step 1). If there is a paper feed request (YES), the following paper 15 using the various sensors 15 (FIG. 2) is used. By determining "What is the type?", "Determination of the paper type" is performed (Step 2). If the result of this determination is "plain paper", the control by "through-up control 1" (Step 3) is performed. If this paper is "special paper" other than "plain paper", "through-up control 2" is performed. Control (S
tep4) is switched and performed. here,
“Through-up control 1” and “through-up control 2” are sheet feeding operations using two types of through-up control methods prepared in advance. On the other hand, if there is no paper feed request, the sequence ends (RET).

FIG. 4 is a flowchart showing a second embodiment of the present invention. In the second embodiment, the "through-up control 1" is set to "normal through-up control", and the "through-up control 2" is set to " Slow through-up control. " That is, specifically, the “normal through-up control” performed in the case of “plain paper” is performed by increasing the pulse rotation speed in a time-series manner as in the related art, so that after a predetermined time has elapsed (after t1 time). Control is performed to set the rotation speed of the stepping motor to the steady rotation (see FIG. 7). In the case of “special paper”, the control method is switched to reach the steady rotation of the rotation speed of the stepping motor as shown in FIG. The control is performed to extend the time (after t2 hours) until the time t. For this reason, as shown in FIG. 5, when the control method is switched to "slow through-up control", the pulse rotation speed increases gradually, and the time to reach steady rotation is also the same as that in "normal through-up control". (T1 <t
2).

FIG. 6 is a flowchart showing a third embodiment of the present invention. In the third embodiment, a paper size detecting means capable of determining a paper type having a large load on the stepping motor as a "specific size". It is characterized in that the step-up motor through-up control is switched according to the paper size of the “specific size” and the “normal size”. That is, as shown in FIG.
Based on the determination of "paper size?", "Determination of paper size type" is performed (Step 2). When the determination result is "normal" paper size, the above-described "normal through-up control" is performed ( In the case of a paper type (specific size) having a large load when feeding an envelope or the like (Step 3), a control for switching to the "gradual through-up control" (Step 4) shown in FIG. 5 is performed. Thus, when the paper is a specific size paper such as an envelope, a gentle motor control (feed operation) with a gradual increase in the number of pulse rotations is performed, thereby reducing motor out-of-step and paper feed failure. Can be prevented.

[0014]

The present invention is as described above. According to the first aspect of the present invention, there is provided a sheet feeding device for feeding a sheet, a stepping motor used for driving the sheet feeding device, and a sheet feeding device. In the image forming apparatus having the paper type determination means for determining the paper type, the through-up control of the stepping motor is switched according to the type of paper determined by the paper type determination means, so that the drive of the stepping motor is reliably performed. And a small and inexpensive stepping motor can be used, and the cost can be reduced.

According to a second aspect of the present invention, in the first aspect of the present invention, when a sheet having a large load on the stepping motor is fed at the time of sheet feeding, the slew-up control for increasing the slew-up time of the stepping motor is performed. Is performed, the driving of the stepping motor can be performed more reliably, and a small and inexpensive stepping motor can be used, so that the cost can be reduced.

According to a third aspect of the present invention, in the first aspect of the present invention, there is provided a paper size detecting means for determining a paper type having a large load on the stepping motor as a specific size. The through-up control of the stepping motor is switched according to the paper size of the paper and the normal size, so that a small and inexpensive stepping motor can be used, and the cost of the sensor can be reduced and the memory source (allowable amount) can be reduced to reduce the cost. There is an effect that can be.

[Brief description of the drawings]

FIG. 1 is a configuration diagram schematically showing an image forming apparatus of the present invention.

FIG. 2 is a block diagram showing a configuration of the control system.

FIG. 3 is a flowchart showing the first embodiment.

FIG. 4 is a flowchart showing the second embodiment.

FIG. 5 is a diagram showing characteristics of the through-up control.

FIG. 6 is a flowchart illustrating the third embodiment.

FIG. 7 is a diagram showing characteristics of a conventional through-up control.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Photoreceptor drum 3 Charging roller 4 Cleaning blade 5 Transfer roller 6 Registration roller 7 Fixing unit 8 Optical unit 9 Paper feed tray 10 Paper feed roller 11 Developing roller 13 Main control unit 14 Controller 15 Various sensors 16 Writing unit 17 High voltage section 18 Fixing section 19 Driver 20 Stepping motor

Claims (3)

[Claims] 1. An image forming apparatus comprising: a sheet feeding unit for feeding a sheet; a stepping motor used for driving the sheet feeding unit; and a sheet type determining unit for determining a sheet type of the sheet. An image forming apparatus characterized in that the step-up motor through-up control is switched according to the type of paper determined by the determination means. 2. The image forming apparatus according to claim 1, wherein when feeding a sheet having a large load on the stepping motor during sheet feeding, a through-up control for extending a through-up time of the stepping motor is performed. apparatus. 3. A paper size detecting means for determining a paper type having a large load on the stepping motor as a specific size, and a step-up control of the stepping motor according to the paper size of the specific size and the normal size. The image forming apparatus according to claim 1, wherein the image forming apparatus is switched.